Electrical system monitoring applications are of increasing importance given recent trends towards electrification driving adoption of renewables and electric vehicles, for example. Thermal and acoustic signatures play an important role in health monitoring while electrical and magnetic field signatures can provide information about operational state. Optical fiber sensors are of particular interest for electrical system applications because of the compatibility with deployment in electrified systems without concerns for electromagnetic interference (EMI) or additional potential risks due to the presence of electrical sensor wires or power at the sensing location, particularly for medium voltage electrical systems. In this presentation, an overview of recent work in optical fiber-based sensing for electrical asset monitoring applications will be discussed in detail. Plasmonic sensors integrated with engineered nanomaterials will be discussed for thermal and other health monitoring applications while interferometric sensors will be discussed for acoustics and also magnetic fields and electrical current sensing. New directions in fiber-based sensing applications will also be discussed moving into the future.
In this work, we demonstrate a reflection-based nanocomposite-functionalized fiber H2 sensor for ease of installation and H2 sensing in energy storage, fuel cells, electrolyzers, and other similar devices. High-temperature H2 fiber probes decorated with Au-Pt bimetallic alloy nanoparticles (NPs) in rutile titania matrix are characterized with scanning electron microscopy (SEM) and grazing incidence x-ray diffraction (GIXRD), and tested experimentally with varying H2 concentration and cycling gas conditions. In response to reducing H2, fully reversible reflectance intensity changes at the alloy NPs’ localized surface plasmon resonance (LSPR) absorption peak are demodulated in real-time. The reflection fiber probe coated with bimetallic Au-Pt NPs in titania show 15x higher sensitivity than corresponding monometallic Au NPs in titania. The demonstration of reflection hydrogen fiber probe provides an installation advantage in various reactor environment applications, and the investigation of the Au-Pt binary alloy system unfolds new sensitivity-enhancing pathways for NP-based LSPR modulation in reducing H2 environment at high temperatures.
Nanocomposite thin-film coated fiber optic sensors can be a promising solution to real-time temperature monitoring of electrical assets and imminent failure detection owing to minimal electrical connections and immunity to electromagnetic interference. However, cost of optical interrogation hardware has been a major roadblock for commercialization of fiber optic sensors. Here, we present a novel and simplified design of a fiber optic temperature sensor based on localized surface plasmon resonance (LSPR) response, a low-cost photodiode transimpedance-amplifier (TIA) circuit and collimated LED for monitoring applications where the cost of deployment is a critical consideration. The TIA circuit is designed to capture temperature-induced optical transmission and reflection responses by photocurrent-converted voltage variations communicated through Serial Peripheral Interface (SPI) wireless communication protocols. Wirelessly interrogable optical fiber sensors can therefore be potentially integrated in a wide range of assets such as grid-scale energy storage and medium or high voltage electric power conversion systems. To further minimize system complexity as compared to transmissionbased sensors demonstrated previously, a major emphasis is on a new reflection-based fiber sensor probe. This is also simulated in an optical waveguide physics-based model with Au-incorporated dielectric matrix oxides deposited on the fiber tip. Preliminary results of modeling the temperature response using end-coated reflection fiber probes are discussed.
pH is a critical parameter for wellbore integrity and geochemical monitoring in wells for oil and gas production, CO2 storage, H2 subsurface storage, and geothermal systems. In situ real-time pH monitoring in subsurface wells is of significant value for wellbore integrity monitoring and predictive analysis of well component deterioration such as casing steel corrosion and cement carbonation. However, harsh environments in subsurface wells have limited many commonly used pH sensors. We have previously demonstrated optical fiber pH sensors coated with metal oxide-based sensing materials such as TiO2, which offer stability at high pressures and temperatures. In this study, we demonstrated TiO2 coated optical fibers for real-time distributed pH monitoring based on backscattered light interrogation. TiO2 coated optical fibers were tested under ambient conditions and wellbore relevant conditions at elevated temperatures. TiO2 coating was deposited on the optical fibers through a facile sol-gel method. TiO2 coated optical fibers have shown promising pH sensing results under elevated temperatures and high pH conditions, making them suitable for wellbore cement monitoring.
KEYWORDS: Transformers, Temperature sensors, Optical fibers, Thermal modeling, Fiber optics sensors, Thermography, Temperature metrology, Magnetism, Finite element methods, Thin films
Reliable, secure, and resilient electricity distribution requires continuous health monitoring of electrical assets including power transformers. Among all sensing parameters, temperature is of utmost importance. Using optical fiber sensors for temperature monitoring has various advantages over traditional methods as they are inherently immune to electromagnetic interference, are good insulators at high-voltage levels, and are easy to install due to their small size and flexibility. Measuring the temperature of different parts of a power transformer core can help to detect hotspots and predict imminent device health issues. In this paper, a low-cost temperature sensor based on plasmonic-enabled optical fiber is demonstrated in multiple arrangements. The simplest arrangement would cost ~ $100 with potential for further cost reductions through reductions in the cost of the detection and excitation circuitry and optical components. By functionalizing an optical fiber with Au-Silica thin-films, the sensor was also demonstrated to measure the temperature of an energized transformer core in real-time. Repeatability and reliability of the proposed sensor were confirmed by running multiple cycles.
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